The Importance Of Storage Domain management.

In today's fast paced world, the changing nature of business has significant implications for the design and deployment of Information Technology (IT) infrastructure. While executive management grapples with adapting the organization to the new business environment, IT is expected to evolve as well, providing the supporting infrastructure necessary to attain business goals. With the growth of the Internet and the emergence of e-commerce as a powerful force across all industries, IT infrastructure decisions play an increasing role in achieving business success. Traditional IT architectures and management paradigms are in many cases proving themselves unable to provide the required flexibility. Characteristics of the new business environment include:

* Rapid, unpredictable change

* Unexpected business obstacles and opportunities

* Significantly condensed business life cycles

* Data as a key enabler of business success

The impact of the new environment on IT, and in particular storage, has been profound. There has been an explosion in the growth of storage, driven in large part by the increasing importance of data to competitive advantage. Access to this data, in fact, often drives competitive advantage. The traditional "direct attach" storage architecture lacks the flexibility to provide high-speed access from multiple servers to essential data amidst rapid, unpredictable change. The escalating costs of the traditional model and, in particular, the management costs associated with that storage have led to a low perceived value for investments made. Storage asset utilization is often sub-optimal. Clearly, the traditional storage architecture is not meeting the requirements of the new business climate.

THE EMERGENCE OF STORAGE AREA NETWORKING

Storage Area Networking (SAN) is a new storage-centric computing architecture that has emerged over the last 18 to 24 months to better enable the IT flexibility demanded by a much faster-paced business climate. Driven in large part by the availability of Fibre Channel-based storage subsystems and network components, SANs promise high speed data access and movement, more flexible physical configuration, improved utilization of storage capacity, centralized storage management, online storage resource deployment and reconfiguration, and support for heterogeneous environments.

In the older "direct attach storage" model, storage resources had a high-speed direct physical path to only a single server. All other servers had much lower speed access to that storage resource only indirectly through the LAN. Storage area networks change that by providing direct, high-speed access paths (through Fibre Channel) from every server to every storage resource in a "networked" topology. The introduction of a network architecture also significantly improves storage configuration flexibility, de-coupling storage resources from a particular server, and potentially allowing them to be managed or configured with minimal impact on server-side resources (Fig 1).

ACHIEVING THE PROMISE OF SANS

The high speed, "any to any" connectivity of the SAN architecture offers significant promise in resolving many of the issues plaguing enterprise storage environments today. Despite their broad potential, practical interoperability issues have kept most SANs relatively small and homogeneous in nature and have limited most deployments to pure connectivity solutions (storage consolidation) or simple storage resource sharing (SAN-based backup). Architecturally, the true promise of SANs is to leverage a consistent set of rich storage management functions across a large number of consolidated heterogeneous server and storage resources that are managed through a single interface and all connected at high speeds through a dedicated storage network. Merely providing the physical connections between servers and storage resources through SAN fabric components such as switches, hubs, or routers is not sufficient to achieve this promise. Significant storage management intelligence is also required to harness the natural a dvantages of this storage-centric architecture against today's most difficult storage management problems.

A critical issue in SAN architecture and design is the location of this storage management intelligence. Traditionally, storage management intelligence has resided in server-based components, but with the rise of intelligent disk subsystems more and more of this management capability has migrated out to the storage resources. Either of these approaches can be reasonably applied to homogeneous environments that have relatively few attached resources (servers, storage), but they quickly become sub-optimal and cost-inefficient in heterogeneous environments requiring higher levels of connectivity. High rates of storage growth are driving businesses to consider consolidation to improve storage management and consolidation of existing resources makes heterogeneous environments almost inescapable. Consolidation will bring products from a variety of different server and storage vendors into a single SAN environment. The dynamics of today's business environment will drive customers to large, heterogeneous SANs--a mode l in which server or storage resource-based storage management intelligence will be sub-optimal.

A third potential location for storage management intelligence is in the SAN fabric itself. This intelligent management capability would supplement the existing SAN hardware infrastructure, building upon its high speed, "any to any" connectivity. From this central location, a variety of heterogeneous servers and storage resources can be supported, and a comprehensive set of storage management functionality managed, through a single interface, can be leveraged against all attached resources. This management capability is called storage domain management.

WHAT IS STORAGE DOMAIN MANAGEMENT?

Storage domain management is a centralized and secure management capability that layers on top of the existing SAN hardware infrastructure to provide high performance, high availability, and advanced storage management functionality for heterogeneous environments. The purpose of storage domain management is to form the core of a robust SAN fabric that can integrate legacy and new equipment, offload SAN and storage management tasks from the servers and storage resources, and host SAN-based applications that can be leveraged across all SAN components. When incorporated into a SAN upon initial deployment, storage domain management provides the foundation to scale seamlessly from small, homogeneous environments to very large, heterogeneous ones with very rich storage management functionality. When added to an existing environment, it adds significant additional storage management functionality, as well as enabling heterogeneity and high-end scalabillity. In this way, storage domain management will make storage ar ea networking a much more powerful tool to address business problems in today's dynamic, high growth storage environments.

THE FUNDAMENTALS OF STORAGE DOMAIN MANAGEMENT

The storage domain management platform must meet certain requirements or it will not provide the full ability to optimize heterogeneous SAN environments. These requirements form a set of five fundamentals that are core to the concept of storage domain management.

HETEROGENEOUS INTEROPERABILITY

With all the server and storage consolidation, as well as the mergers and acquisitions common in today's new business climate, heterogeneity is a fact of life in enterprise environments. A set of products that provides SAN functionality for a single vendor's product line is not sufficient for customers to achieve the full promise of SANs. Customers need an ability to preserve investment in legacy equipment even as they add and take advantage of new server and storage products, and therefore a storage domain manager must support Fibre Channel and SCSI attachment at a minimum. The platform should be able to provide a well-defined growth path to more extensive multi-protocol connectivity because the storage domain manager will need to evolve over time to accommodate newer technologies as they are introduced.

Interoperability certification prior to production deployment is an absolute requirement in enterprise environments. To meet this requirement, a storage domain management vendor should provide facilities to help customers test and deploy proven heterogeneous configurations. A SAN Interoperability Lab with dedicated staff and a wide array of server and storage resource products from all the major vendors must be available, and the storage domain management vendor must be willing to work with its customers to test and certify specific configurations.

SECURE, CENTRALIZED MANAGEMENT

SANs create a large, virtualized storage pool that can be managed centrally to minimize storage management tasks relative to the traditional "direct attach" storage architecture, particularly in the areas of backup/restore and disaster recovery. Security must be addressed in a robust manner because SANs effectively provide a physical access path from all servers to all storage, but all storage should not logically be accessible to all servers. SAN fabric vendors do this through the logical definition of "zones" with each server only able to access data defined as being within its zone. Clearly, the ability to define secure zones, or storage "domains", is a key requirement for a storage domain manager. Improved granularity of domain definition, such as defining inclusion within a zone at the LUN level rather than at the device or port level, offers significant additional flexibility in improving storage asset utilization over time.

Probably the most critical capability a storage domain manager must offer is a comprehensive set of centralized storage management capabilities that can be leveraged, from a single management interface, across all attached servers and storage, regardless of vendor. If, from a central location, a system administrator may control the movement or mirroring of data between heterogeneous storage resources and can dynamically leverage these capabilities across different heterogeneous storage resources over time, this can result in a significant cost savings and simplification of administrative complexity. As a scalable, intelligent platform, the storage domain manager resides in the perfect central location to host storage management functionality that can be leveraged across all attached server and storage resources. Instead of licensing and learning vendor-specific storage management features many times across different servers and storage resources, a single copy of storage management software, running on the st orage domain manager, is very cost-effectively leveraged across all the SAN resources (Fig 2).

SCALABILITY AND HIGH PERFORMANCE

Given the storage growth rates driven by the new business climate, a specific SAN environment may easily grow two orders of magnitude in storage capacity during its lifetime. As the point of central intelligence in the SAN, a storage domain manager must be able to accommodate a significant amount of growth without load-related performance degradation. Intelligence should be added as configurations grow to ensure smooth, cost effective scalability over a wide performance range.

An ability to cache significant amounts of data in the intelligent platform itself is crucial in optimizing the SAN configuration to achieve performance improvements in application-specific environments. For example, if "hot spots" such as file system journals and database table indexes or logs can be cached in high speed storage in the storage domain manager itself, this significantly minimizes latencies relative to more conventional SAN configurations built without a storage domain manager. Given a sufficient amount of onboard storage, entire databases and file systems can effectively be cached to achieve large performance improvements. The on-board storage capacity is also important to stage data during migration and other data movement tasks.

ENTERPRISE CLASS RELIABILITY, AVAILABILITY AND SERVICEABILITY (RAS)

As mentioned earlier, one of the key reasons for moving to a SAN is to improve overall data accessibility. If single points of failure are introduced as a result of the move to this new storage architecture, many of its potential benefits may not be realized. For this reason, not only the data itself but also the access paths to that data must be available at all times. Minimizing downtime due to failures must be addressed through the use of reliable internal components and capabilities such as automatic I/O path failover, logical hot sparing and pluggable, hot swappable components. Downtime must be further minimized through on-line management capabilities such as on-line firmware upgrades, dynamic hardware and software reconfiguration, and high-performance background data movement.

AN INTELLIGENT, PURPOSE-BUILT PLATFORM

To ensure the highest levels of performance, the storage domain manager must be an intelligent purpose-built platform specifically optimized for the storage related tasks demanded of it. Leveraging the latest in 64-bit RISC processor technology, this platform must support significant local processing power to perform a wide range of storage management tasks and must be backed by the local high speed storage necessary for data movement and storage management application execution.

In comparison with a general-purpose platform being used as an intelligent storage server, a purpose-built platform would offer a real time operating system for much faster and more deterministic response time, more efficient I/O path code to minimize message latencies, and an operating system kernel optimized as a data mover engine rather than an application engine. This purpose-built platform would also support kernel-level features not available in a general-purpose operating system, such as reliable, deterministic message delivery run-time reconfigurability, and very low overhead for real-time operations tracking. High availability features such as integrated path failover, on-line management, and dynamic reconfiguration would be supported by the core operating system. By providing intelligence in the optimal location to support heterogeneous SAN environments, the storage domain manager can deliver the following business benefits to end-users:

* Improved storage asset allocation and utilization

* The flexibility to cost-effectively accommodate dynamic, high growth storage environments

* Higher availability through on-line management and configuration

* More efficient management to lower the overall $/GB costs of storage administration

* An ability to consolidate heterogeneous servers and storage in an integrated SAN environment

* Increase the value of JBOD storage by adding storage management and caching features that can be dynamically leveraged across all storage resources

SANs offer a new, more flexible storage architecture that can help organizations meet the growing demands for ubiquitous access to highly available data in today's fast-paced business climate. However, the SAN hardware architecture must be supplemented with a SAN fabric-based storage management intelligence called storage domain management in order to support the large, heterogeneous SANs needed to address today's enterprise-computing requirements. While server and storage-based storage management intelligence can potentially address the requirements of smaller, more homogeneous SAN environments, the business environment dynamics will drive cost-conscious customers to large, heterogeneous SANs where storage domain management is a requirement.

SUMMARY

Storage domain management is the secure, centralized management capability that layers on top of the SAN hardware infrastructure to provide high performance, high availability, and advanced storage management functionality for heterogeneous SAN environments. Investment protection is ensured by a modular architecture that supports SCSI, Fibre Channel, and, in the future, will allow for the easy integration of additional multi-protocol support. The fundamentals of storage domain management are:

* Heterogeneous interoperability

* Secure, centralized management

* Scalability and high performance

* Enterprise class RAS

* An intelligent, purpose-built platform

Storage domain management can be added to existing SANs or incorporated at initial SAN deployment to provide the flexibility to accommodate an environment of rapid, unpredictable change while still providing secure, high-speed access to highly available heterogeneous storage with very rich storage management functionality. The resulting centralized storage management paradigm is a more efficient, less costly way to manage the growth of the data that drives competitive advantage for the enterprise.

Eric Burgener is the director of product marketing at ConvergeNet Technologies (San Jose, CA).

* Heterogeneous Interoperability

* Secure, centralized management

* Scalability and high performance

* Enterprise class RAS

* An intelligent, purpose-built platform